Australian Flowering Plants. 203 



the presence of a latex and the ability to modify the leaves 

 and stems ; this is also apparent in the Apocynacese and the 

 Asclepiadacese ; in Verbenacese and Labiatas, it was the presence 

 of essential oils and the special provisions in the leaves against 

 excessive transpiration. In Sapindacese and Sterculiacese it was 

 the presence of viscid substances as also special provisions in 

 the leaf and the root. In Liliaceaa and Orchidacese it was the 

 bulb, the peculiar leaves, and the development of the herbaceous 

 habit which helped so materially in the growth of the great 

 endemic genera. In the Apocynacese and Asclepiadacese, how- 

 ever, the plants were not equipped so well to face the cold, and 

 as with Myoporinacese, they are not so much to be found on the 

 extratropical sandy soils as on the more tropical subarid areas. 



In each case they are the vigorous, numerous, aggressive, and 

 many-specied genera of Australia, which appear to chafe at the 

 limits which the Australian island continent has placed upon 

 them and which appear to demand new territory in which to 

 develop still further ; in other words, they act as though they 

 were new and aggressive types, born of a common necessity. 



With the rare exceptions mentioned above these great genera 

 occur together in any of the large sandy areas of temperate 

 Australia and those types, in the genera Eucalyptus and Acacia, 

 which are to be found on the rich heavy soils may be seen, by 

 their morphology, to be more highly specialized, and to be more 

 recent in their origin, than the great mass of the sandstone flora 

 types. In no case has any large genus, any subtribe, or any 

 tribe, of Australia been produced away from the barren sandy 

 wastes ! 



(5) Euphorbiaceoe, Labiate, Verbenacece, Pittosporaceaz, Treman- 

 dracew, Liliacece. 



Euphorbiacew. In this great family, the sandstones pro- 

 duced the endemic tribe Stenolobese with 11 genera, and about 

 SO species, and as with all the other great families in Australia, 

 no other endemic tribe, subtribe, or large genus of this family, 

 was developed except on the peculiar hungry sandstone areas 

 of Australia. 



Labiatw. In this great family the hungry sandstone areas 

 practically possess the whole of the endemic tribe Prostan- 

 thereaa with 5 genera and about 100 species. 



Verbenacew. The tribe Chloanthese here included is endemic 



with 10 genera and about 40 species, all being practically 



limited to the sandy soils and as with the Labiates and other 



Am. Jour. Sci. — Fourth Series, Vol. XLII, No. 249.— September, 1916. 

 14 



